Unit fuel injectors are well known in the art for controlling the timing and volume of fuel being injected into respective combustion chambers of an engine. Typically, many of these unit injectors are mechanically or hydraulically actuated. In most applications currently used, the timing of the respective injections are controlled electronically based on various system parameters. In one example of these known unit injectors, fuel is delivered to a pumping chamber through an electrically controlled valve assembly and a plunger piston acts in response to rotation of a cam arrangement moving the plunger piston to force the fuel from the pumping chamber. When the electrically controlled valve assembly is closed, the fuel is forced towards a pressure responsive check valve and subsequently to a fuel nozzle for injection into the combustion chamber of the engine. When the electrically controlled valve is open during the movement of the plunger piston, the fuel is forced to flow back into the low-pressure fuel gallery. In many of these known systems, unstable pilot injection may occur. These unstable pilot injections may be a result of fluctuations in the pressure in the system due to the fluid dynamics therein. An example of such as system is illustrated in U.S. Pat. No. 5,494,220 which issued on Feb. 27, 1996 to R. D. Shinogle et al. This patent attempts to offset pressure variations around the periphery of the valve seat in order to prevent or minimize weakening of the fluid seal at the valve seat. The pressure variations are typically a result of sudden changes in fluid flow within the unit injector that result in undesirable pressure fluctuation (spikes). Likewise, these pressure spikes may also cause cavitation at the nozzle tip during injection of fuel into the combustion chamber.
The subject invention is directed to overcoming one or more of problems as set forth above.